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89 lines
2.2 KiB
C++
89 lines
2.2 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03
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// <tuple>
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// template <class TupleLike> tuple(TupleLike&&); // libc++ extension
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// See llvm.org/PR31384
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#include <tuple>
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#include <cassert>
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int count = 0;
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struct Explicit {
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Explicit() = default;
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explicit Explicit(int) {}
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};
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struct Implicit {
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Implicit() = default;
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Implicit(int) {}
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};
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template<class T>
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struct Derived : std::tuple<T> {
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using std::tuple<T>::tuple;
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template<class U>
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operator std::tuple<U>() && { ++count; return {}; }
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};
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template<class T>
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struct ExplicitDerived : std::tuple<T> {
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using std::tuple<T>::tuple;
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template<class U>
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explicit operator std::tuple<U>() && { ++count; return {}; }
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};
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int main() {
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{
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std::tuple<Explicit> foo = Derived<int>{42}; ((void)foo);
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assert(count == 1);
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std::tuple<Explicit> bar(Derived<int>{42}); ((void)bar);
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assert(count == 2);
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}
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count = 0;
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{
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std::tuple<Implicit> foo = Derived<int>{42}; ((void)foo);
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assert(count == 1);
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std::tuple<Implicit> bar(Derived<int>{42}); ((void)bar);
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assert(count == 2);
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}
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count = 0;
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{
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static_assert(!std::is_convertible<
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ExplicitDerived<int>, std::tuple<Explicit>>::value, "");
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std::tuple<Explicit> bar(ExplicitDerived<int>{42}); ((void)bar);
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assert(count == 1);
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}
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count = 0;
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{
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// FIXME: Libc++ incorrectly rejects this code.
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#ifndef _LIBCPP_VERSION
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std::tuple<Implicit> foo = ExplicitDerived<int>{42}; ((void)foo);
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static_assert(std::is_convertible<
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ExplicitDerived<int>, std::tuple<Implicit>>::value,
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"correct STLs accept this");
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#else
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static_assert(!std::is_convertible<
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ExplicitDerived<int>, std::tuple<Implicit>>::value,
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"libc++ incorrectly rejects this");
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#endif
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assert(count == 0);
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std::tuple<Implicit> bar(ExplicitDerived<int>{42}); ((void)bar);
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assert(count == 1);
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}
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count = 0;
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}
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